San'yōdō in the context of "San'yō Main Line"

Mimasaka Province (美作国, Mimasaka no Kuni; Japanese pronunciation: [mʲi.maꜜ.sa.ka (no kɯ.ɲi)]) was a province of Japan in the area that is northern Okayama Prefecture in the Chūgoku region of western Japan. Mimasaka bordered Bitchū, Bizen, Harima, Hōki, and Inaba Provinces. Its abbreviated form name was Sakushū (作州). In terms of the Gokishichidō system, Mimasaka was one of the provinces of the San'yō circuit.

Under the Engishiki classification system, Mimasaka was ranked as one of the 35 "superior countries" (上国) in terms of importance, and one of the "near countries" (近国) in terms of distance from the capital. The provincial capital was located in what is now the city of Tsuyama.

Suō Province (周防国, Suō no Kuni; Japanese pronunciation: [sɯꜜ.oː (no kɯ.ɲi)]) was a province of ancient Japan in the area that is today the eastern part of Yamaguchi Prefecture. Suō bordered on Aki, Iwami, and Nagato Provinces.

Its abbreviated form name was Bōshū (防州). In terms of the Gokishichidō system, Suō was one of the provinces of the San'yōdō circuit. Under the Engishiki classification system, Suō was ranked as one of the "superior countries" (上国) in terms of importance, and one of the "far countries" (遠国) in terms of distance from the imperial capital, Kyoto. The provincial capital was located in what is now the city of Hōfu, Yamaguchi. The ichinomiya of the province is the Tamanooya Shrine also located in Hōfu.